Rick Perlstein: The NY Sun can't decide whether to be pro or con about his Nixonland book

The conservative NY Sun has published two reviews of Rick Perlstein's Nixonland. The first review, published at the end of May, was glowing:

You don't have to agree with everything in this monumental account of politics in the 1960s and 1970s to find Rick Perlstein's"Nixonland" (Scribner, 896 pages, $37.50) interesting and even engrossing. The book is a masterful retelling of the turbulent period between the crushing defeat of Barry Goldwater by Lyndon B. Johnson in 1964 and the equally stunning loss by George McGovern to Richard Nixon in 1972.

Then came this from the pen of Conrad Black, the disgraced businessman who moonlights as a historian: